Practica Oto-Rhino-Laryngologica

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Saccade was analyzed quantitatively by a small general purpose digital computer (PDP 11/40), which measured latency, maximum eye speed, and accuracy. The details of the method of analysis were basically those reported previously.
Investigations of the best stimulation conditions and factors which influence the analysis were added.
First, 12 normal subjects aged 18-27 years were examined.
The average latency was 225msec, with a standard deviation of 43msec; there was no relationship between latency and target amplitude. For maximum eye speed, the power-law curve Y=K1×X^K2 was used, where Y=maximum eye speed, X=saccade amplitude, K1 and K2=constants returned by the curve fitting program in degrees per second. When the power-law curve was fitted to the amplitude-maximum eye speed, K1 was 57.227 and K2 was 0.6707.
For accuracy, the relationship between target amplitude and saccade amplitude was examined. It closely resembled the form Y=0.9514X+0.1340, and there was a high correlation between them.
Next, examinations were performed on 104 patients with 13 different disorders; 1. cerebral legion, 2. Parkinson's disease, 3. cerebellar legion, 4. spinocerebellar degeneration, 5. methylmercury intoxication, 6. brainstem legion, 7. cerebello-pontine angle legion, 8. vascular disorder, 9. other central legions, 10. congenital nystagmus, 11. gaze nystagmus of unknown origin, 12. myasthenia gravis, 13. peripheral legion.
Patients with spinocerebellar degeneration, methylmercury intoxication, or myasthenia gravis had elongation of latency (p<0.05). Patients with brainstem legions had significant slowing of maximum eye velocity. Some patients with spinocerebellar degeneration, methylmercury intoxication, cerebellar legions, or myasthenia gravis had slowing of maximum eye speed. In accuracy tests, patients with cerebral legions, Parkinson's disease, spinocerebellar degeneration, or methylmercury intoxication had hypometria or inaccurate saccade amplitude.

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